WndDbg with SCSI Miniport

WINDBG
1

I am using WndDbg 6.1.0017.2 to debug a SCSI miniport driver. The problem
that I am having is that the debugger is behaving very strangely. Below
are some of the symptoms:

  1. After hitting a break point within a function not all of my Local
    variables are being display (View->Locals). The ones that are displayed
    are fequently wrong.

  2. When single stepping through code the debugger frequently does not step
    through correctly – it will jump around. Although the code is executed
    correctly.

  3. Using DebugPrint the data is not always displayed correctly. It is just
    plain wrong for some reason.

This miniport is being developed for Win2K. I have used WinDbg v 5.xx and
have gotten the same exact problems.

Does anyone have any idea what might be wrong here? Is there a different
method for debugging miniports? BTW: I have verified that symbols are
correct.

Thanks,
Dale

2

Missing locals and “jump around” while stepping is because you are
debugging optimized code.

The optimizer does optimize away vars & does rearrange code. If you
wish to understand what the compiler did then it is helpful to have the
compiler generated an ASM/source mixed listing file.

The easiest thing to do is to debug unoptimized code. However you can
never get 100% away from debugging optimized code, so some practice is a
good thing…

Don’t have enough info to know if your wrong data issue is caused by
optimizeation or not. I could see in some scenerios that the
optimization may invalidate your assumptions of what the value should be
at a given time.

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of
xxxxx@hill-eng.com
Sent: Friday, October 31, 2003 4:35 PM
To: Kernel Debugging Interest List
Subject: [windbg] WndDbg with SCSI Miniport

I am using WndDbg 6.1.0017.2 to debug a SCSI miniport driver. The
problem
that I am having is that the debugger is behaving very strangely. Below
are some of the symptoms:

  1. After hitting a break point within a function not all of my Local
    variables are being display (View->Locals). The ones that are displayed
    are fequently wrong.

  2. When single stepping through code the debugger frequently does not
    step
    through correctly – it will jump around. Although the code is executed
    correctly.

  3. Using DebugPrint the data is not always displayed correctly. It is
    just
    plain wrong for some reason.

This miniport is being developed for Win2K. I have used WinDbg v 5.xx
and
have gotten the same exact problems.

Does anyone have any idea what might be wrong here? Is there a different
method for debugging miniports? BTW: I have verified that symbols are
correct.

Thanks,
Dale

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3

No this is not a code optimization problem. The “jumping around” is
different then that – you’d have to see it. Having your local go away is
defintely not a code optimization problem. Thanks any way.

4

Hmmm and you know this for a fact? You realize that you just blew off one of
the MS fells that has been providing Windbag support for about 5 years? But
then I guess you know better then he.

“Jumping around” most definitely IS a code optimization problem. I’ve been
using Windbag for almost 10 years and the ONLY times I have “jumping around”
problems is when I was running the RELEASE version with optimization or had
accidentally turned it on in the checked version. And frequently that is
because I was testing the release build, found a problem, and FORGOT to
replace it with the checked build before I started the debugger.

–
Gary G. Little
Seagate Technologies, LLC

wrote in message news:xxxxx@windbg…
>
> No this is not a code optimization problem. The “jumping around” is
> different then that – you’d have to see it. Having your local go away is
> defintely not a code optimization problem. Thanks any way.
>
>